Improved understanding of complex living cell function is important in the fields of science and medicine. Knowledge of cell activity may be gained by measuring and recording electrical potential changes occuring within a living cell. Value of research measurements are enhanced when the physical and electrical environment of the cell under study may be controlled during measurement.
Intracellular electrical measurement has application in research studies of nerve cell bodies and tissue culture cells such as smooth muscle, cardiac, and skeletal muscle. Such measurements and suitable display are also useful for demonstration in teaching laboratories.
Microelectrodes are currently used for recording activity from cell bodies of neurons. Two types of microelectrodes are generally available. One method uses a finely drawn glass tube with a sample opening of about 1 micron in diameter. The tube is filled with a conductive fluid. The liquid filled tube becomes a measuring electrode, or probe, which is inserted in the cell by use of a micromanipulator. The second method employs a fine wire with a sharpened point as the electrode. Electrical signals detected by electrodes are amplified, displayed, or recorded by equipments connected to the microelectrode.
Microelectrodes require great skill in fabrication and use. Due to their small size and light structure, difficulty is encountered in positioning the sample cell and insertion of the microelectrode. Maintenance of good electrical contact is often hard to achieve because the delicate connection to the cell is vulnerable to movement or vibration which alters electrical parameters, or breaks the circuit altogether. Further, methods of circuit connection and completion vary, and often prevent microelectrodes from providing the rapid response time sufficient to record many of the very fast events occuring in a nerve cell. Microelectrodes also do not provide for readily changing the intracellular environment of the cell membrane during measurement and study.
It is therefore desirable in research studies of nerve and tissue cells to have a compact integrated electrode which holds the sample cell firmly, has rapid time resolution, and permits changing the intracellular environment of the studied cell.